Apparatus and procedure for sensing passage of moving thread or the like



Nov. 24, 1964 G. E. SCHACHER 3,153,352

APPARATUS AND PROCEDURE FOR SENSING PASSAGE OF MOVING THREAD OR THE LIKEFiled Aug. 23, 1960 W: men/0r 54 48 ff f 9 Gore/0n 550/206/76/ g, 6mats. MM

H- l. 1 l i.- ti I, I PPAR US .AN PBEDU E FOR. S NS PASSAGE o1? Movnqr;THREAD on 'iHELiKE ran as, enter; new an i a N '7 via venture, Mamm cansFiled Aug, 23; 196%, Ser. No, 51,374 8 Claims. (Ci. 340-259) Thisinvention relatesto apparatus and procedure for deteoting passage of amoving article, and more particularly for sensing the presence orabsence of a thread, filament or the like which is passing continuouslythrough a given region, In a more specific sense the inventionisconcerned with detecting interruption in the passage of thread inteirtile apparatus, as where such thread is continuously advanced forwinding or for spinning or for use in knitting or other operations.

For convenience; the term thread is used herein to include genericallysimilar" filamentous material $1 9 as yarn, roving and otherfibrousstrands such as synthetic 3,158,852 P a tented Nov. 24, 1964 bodies, ofwhich instances are synthetic filaments and apparatus.

bundles of filaments of any composition whatever, ranging from rayon toglass; are intended by the term textile Such term likewise includesknitting, weaving, sewing, braiding, and like t'nachines," where threads.are continuously transported and there is need to detect anyinterruption in thepassing' thread.

Principal objects of the inventionare therefore to provide novel methodsand apparatus for sensing the occurrence of the passing yarnor the likeand for providing a signal, as for indication, or control purposes,

' when the thread is broken or otherwise fails to follow itsdesiredcourse in thedoperation of the equipment. Further objects are toafford new photoelectric means for detecting interruption in threadpassage and for establishing signals representing any breakage or otherstop page of the passing thread, or alternatively providing a filamentsor bundles of such filaments. Ina more gen eral sense, unless limited totextile thread as just described (which includes sewing threadtthe termis intended to include other filamentous articles such as Wire, cord,string, twine, strands for cordage, and the like.

In one particular embodiment of the invention, it is associated withyarn-spinning machinery, where, for example, a continuous thread-likearticle is drawn from one or more supply bobbins, such article beingspecifically one or more so-called 'rovings, and where the roving isthen continuously wound on a receiving bobbin, as yarn, the windingoperation including a twisting action for imparting the desired twist toconstitute the fibrous material yarn. In spinning machines of this sort,the roving or yarn continuously travels through a space between thesupply, bobbin or spool and the receiving bobbin. Ordinarily themachinecomprises a large multitude of assemblies of the characterdescribed, thus simultaneously producinga corresponding number ofbobbins of spun yarn.

the need to'watch carefully for the occurrence of breaks signal when theoperation is continuing as desireda Additional objects are to providenew means and methods for photoelectric detection ,of passing objects,particularly objects undergoing oscillation or vibration;

In various types of textile equipment or the like, as exemplified byspinning and knitting machines, the yarn travels fromone locality toanother, through' an intervening'space, in such fashion that it iscontinuously in vibration. Thus in spinning equipment, the roving isbrought down from the supply spools, through a" suitable eye or guideand then to the winding and spinning structure, conventionally involvinga travelerjfollowing a circular path around, a collecting bobbin so thatas the yarn is wound on the rotating bobbin, it traces a conical surfacedefined by the circul-artpath, such action afifording the desired twistin the yarn. By virtue of this oscillating movement,,the yarn above-theeye is set in vibration, e.g. of a circular or cylindrical typepwhichmay be readily seen, or which indeed may be so minute as to bedifiicultly perceptible, v r

In accordance with the present invention,- photoelectric means aredisposed adjacent the path of the yarn where itundergoes thelast-mentioned vibration, together with appropriate illurnin'ation, insuch relation that the light received by thelphotoelectnic means ,hasaperiodic in any of the manymoving threads, so that appropriately promptattention can be given to mending the break or otherwise correctingthemalfu nction of the given unit of the apparatus. To maintaindesirable efiiciency in the use of such equipment it has therefore beennecessary for an attendant or operator to inspect the'machine almost allthe time. This is a difiicult task, especially where the machine orgroup of machines may involve as many as hundreds-of spinning units,each with its individual yarn or roving to be watched.

A similar problem occurs in knitting machines, where yam continuouslytravels from a supply bobbin or spool,

through the intervening space, to theknitting mechanism itself. becausethe knitting machine must immediately be stopped, i.e.-whe'n the yarnfails by breakage or other occurrence. So far asI am aware, no effectiveWay has heretofore been 'foundtto detect interruptions of thread passagein apparatus of these types, other than electromechanical devices, whichby their nature must physically touch the thread andcan therefore causebreakages, This trouble is especially acute With threads that are beingspun and thus are very weak.

For brevity of reference herein, the term textile nachi'ne is adopted as-a generic designation for equipment of this sort, ile. includingspinning'and yarn-handling machines as use'din producing yarn. Thus thevarious types of machines used in spinningnatural fibrous materials,aswell as apparatus for producing, spinning, winding or otherwisetreating" various similarfilament'ous' or oscillating character torexample being interrupted orreduced in an oscillating manner by thevibrations of the yarn By an appropriate circuiha pulsating voltagepriate r ectifying means, to control the output circuit in Indeed here,the problem is particularly acute accordance with the presence orabsence otthe A.C.

signal. Suitably relay or other means in such output circuit areconsequently arnanged to yield a significant signal, e.g. upon failureof thethread. Such may in volve a visible or audible indication, asby alight or hell, or may arranged for control or recording purposes;

Thus in the case of a spinning machine, the described instrumentalittiesare: organizerl to afford a visible or audible signal vupon"breakage orthe yarn and absence of the pulsating output of the photocell, U Theloperatoris then Warned to locate and" repair brnken thread. other typesof textile machinery, similar signals may be em- Pl t Q s b vt as atantennae the output signal representative of threadbreakagq nay bedirected to stop; the machine, asibyksuitable control ofthe' circuit forea rgizingja driving motor.

Easing thread is t sets a t scr n n its characteristics, or the" like;Whereas attempts to'detect 3,1 eases the presence or absence of a threadby direct measurement of the DC. output of a phototube have beenessentially unsuccessful, largely because the light-modifying efi'ect ofthe thread, with respect to the total quantity of light, is so slightand is so easily masked by variable factors as just outlined, thepresent system is unusually satisfactory. As will now be appreciated,the voltage output of the photocell circuit is essentially modulated orrendered pulsating, by the vibration of the thread. This pulsating oroscillating component of the electrical output is separated or convertedas an alternating current signal, which thus is detectably present or isabsent, in direct and necessary response to the condition of the threadalone. Hence the signaling function of the system is completely positiveand is not confused by other factors.

The invention may be further explained by reference to the accompanyingdrawing, wherein:

PEG. 1 is a somewhat schematic view, in elevation, of the related partsof one unit of a spinning machine, in

combination with the optical parts of the present inven- Y tion, asillustrating one embodiment of the latter;

FIG. 2 is a diagrammatic elevation of the-vibrating thread region inFIG. 1, taken as seen from the left-hand side of FIG. 1;

FIG. 3 is a fragmentary plan view of the optical elements as seen online 3--3 of FIG. 1;

FIG. 4 is a view similar to FIG. 3, with a slightly different relationof the elements to the passing thread; and

. FIG. 5 is a diagram of one form of electrical circuit constituted inthe invention, as in combination with the structure of FIG. 1.

For purposes of illustration, the drawing shows the invention as relatedto spinning apparatus, where one or more strands of cotton roving lit)are withdrawn from a spool or bobbin 12 and eventually twisted andrewound on a bobbin 14, it being understood that in some cases two ormore strands of roving are combined to constitute a single thread oryarn cluster 10, i.e. from a corresponding number of bobbins 12, or froma large number of threads on one bobbin (or card).

As dragrammatically shown, the roving may pass through a conventionaldraft section or unit 15, where drawing rollers attenuate the fibrousthread. From the draft section the thread it), now attenuated as desiredfor yarn, traverses, first, a tubular guide 16, which may also impart atwist to the yarn, and then at a lower locality, a further guide element17, e.g. in the nature of an eye or eyelet of glazed ceramic. The threadthen follows a path conventional for the spinning and rewinding action,for example as in passing through a so-called traveler 18, which isfreely movable around the circular periphery of a ring guide 19 carriedby a ring rail 2% that is appropriately displaced in a verticaldirection for winding i the yarn on the bobbin lid. The ring guide 19surrounds the vertical bobbin which is continuously rotated at a highspeed. As the yarn is thus wound upon the bobbin 14-, the arrangementillustrated drags the traveler around the ring, i.e. so that the yarnIt) (being the attenuated roving) is twisted into the desired yarnformation.

It will be understood that modified or other structures for the spinningoperation can be employed as may be desired, for example as with respectto arrangement of guides, twisting and winding elements, and so forth.The essential features of the assembly are that the yarn at one end ofits path is given an oscillatory or equivalent motion, so that in anappropriate part of the path it exhibits a detectable vibration, usuallyin the nature of a trace of a surface of revolution, e.g. as seen in thecentral locality 22. where the thread passes between the guides 16 and17. Although in this instance the vibration is transmitted from thelower motion of the thread in a cone-shaped path, other situations orconfigurations of vibratory motion of the thread may be utilized, evenincluding upper portions of the cone-shaped oscillation pur red by theyarn in its twisting and winding action.

In spinning operations of this sort where a single machine may have a.great many units of the sort illustrated in P16. 1 for correspondinglysimultaneous production of a large number of bobbins of finished yarn lt, it is important to ascertain promptly the occurrence of a broken yarn(i.e. roving) in any of the units, or any stoppage of the yarn travel orany premature or unexpected termination of the length of yarn. To suchends, the invention includes a photoelectric cell 24 disposed at oneside of the region 22 of thread travel, and a source of light such as asmall incandescent bulb 25 at the opposite side of the region 22, thelamp having an appropriate energizing circuit 26. Suitable collimationis also included, as by means of the collimating tube 23 which surroundsthe photocell 24 and extends a considerable distance into proximity withthe vibrating thread 16a at the region 22. Thus to a considerableextent, the light reaching the photocell 2 5- is restricted to thatwhich originates in the source 25,.although the nature of the system,and its selectivity of response to the pulsating or alternating signalare such that a high degree of exclusion of external light is usuallyunnecessary.

Although as indicated above, the difference in light transmission whichwould be occasioned by the presence or absence of a stationary threadwould be easily masked by other changes in light or by variable factorsin the photocell or its circuit, or would be confused with the resultsof such changes, the vibrating character of the thread ltla provides ahighly distinctive modification of the light received by the photocell.Specifically it isfound that the electrical output of the latter thenincludes a pulsating or alternating component, corresponding to thefrequency of vibration, which is readily detectable apart from theelectrical effect simultaneously repre sented by more or less constant(or at least non-oscillatory) impingement of light. If desired, thecenter line about which the thread vibrates may be displaced partlysidewise of the central axis of the collimated light path between thesource and the photocell, as indicated in FIG. 4, at ltlb. Thisarrangement insures that there is an oscillating variation in the totallight received by the photocell 24 from the source 25, while the threadis vibrating. It is found, however, that good results are also obtainedwhere the central, vertical line of the vibrating thread intersects thecentral axis of the collimated light path and is thus disposed inalignment with the center of the photocell; although theory mightsuggest that in a perfectly symmetrical relation, there would be noreduction in light because of vibration of the thread, it appears thatby reason of the nature of the light source, the characteristics of thephotocell electrode structure and other necessary inexactness ofmechanical arrangement, such theoretical result does not occur, butthere is always suflicient inherent asymmetry of light-block ing orphotocell response as to impose oscillations in the electrical eifect ofthe cell.

Although other circuits, including arrangements using transistors orother types of electrical amplifying or translating means, may beemployed, FIG. 5 shows an example of a simple electronic system forhandling the electrical output of the cell and for translating thecorresponding alternating electrical signal representative of threadvibration, into a desired output response, e.g. so as to atford aworking signal when the thread breaks and its vibration disappears.Described generally, in the system of FIG. 5, the alternating componentof the phototube, 24 is amplified as an alternating current signal bythe tube 36 The amplified A'.C. voltage delivered by the last-mentionedvacuum tube is rectified by the rectifier 31, which feeds a D.C.amplifier constituted by the vacuum tube 32. Thus the alternatingcurrent signal representative of vibration of the thread llt a becomesa, DC. signal in the plate circuit of the tube 32, energizing a suitabletranslating device such as the relay 34. The

relay may be arranged to eontr'ol a final output circuit 35, iLe'. byclosure of relay contacts 36 upon deenergiza-' 1 tion of the relay, sothat a working electrical signal is produced in the circuit 35 when theAC. signal from the photocell disappears because the vibrating thread16a is broken or has stopped vibrating. For simplicity of illustration,the circuit 35 is shown as including a" source of current 38 and one ormore signaling or other'trlans lating or control devicessuchas a signallamp 39 and a bell40. Hence the arrangement is such that when thethreadbreaks, so that there is no vibrating element affecting the light to thephotocell and correspondingly modulating the photocell output, a visiblesignal, or an audiblesignal, or both, will be given immediately.

As already described, the illustrated apparatus, and the method involvedin operating it in .the stated manner,

provide a highly reliable watch or monitoring of the con-- dition of thethread 10- in the spinning or like machine. As long as" the threadsupply lasts, and there is no breakage and the spinning operation aroundand upon the bobbin 14' continues as desired, the alternating currentsignal from the photocell will persist. In consequence, for example, theoutput circuit35 is kept open. Should the thread 10 break, at anypointin its course, there will be an immediate cessationof vibration atthe region 22, so thatthere will no longer be a vibrating threadcondition affecting the light to the cell 24. In consequence, thealternating electricalsignal disappears, whereupon a working signal isautomatically produced in the cireuit 35, with consequent establishmentof a" visible or audiblewarnin'g, which persists so long as" the threadbreakage or other malfunction has not becn corrected. The machineattendant is thus promptly notified that a spinning unitis in trouble,and been readily find it and correct the difiiculty. Indeed it will beapparentthat each of a large number of spinning'units in the machine maybe accompanied with photoelectric means and circuits controlled therebyas in FIGS. l and 5, to actuate a single warning device (light, hell orthelike) upon thread breakage at anyone of the units. It is ordinarilynot difiicult to findthe non furictioning unit under such cir I,

cumstancea yet: the system avoids the tedious and time'- consuming taskof constant watch over the units to learn of the fact of a breakage atany place. It is also possible to have a warning signal at each spinningto eliminate searching the entire machinefor the defective unit.

It will be readily apparent that the system is essentiall-y foolproofand highly reliable; For exampleif the intensity of illumination fromthe light source or eXoiter lamp 2 5 should change, there is no dangerof improper response, since the translating circuits are controlled onlyin accordance with the presence or absence of an alternating componentof the photocell output. Non-oscilliatory or non-periodic changes haveno efiect, nor Within a relatively large range, is there any effectbecause of change in amplitude of the AtCysignal. In other words, the

system may be described as automatically a'djusted'to' the intensity ofilluminati'on fronr the lamp 25, when" such intensity changes.

The circuit is similarly free of improper function or lack of desiredresponse, because of other casual changes,

e g. in power supply, phot otube characteristics, orthe like. At thesame time, the apparatus is of a fail-safe character, since anycircuitfailure will interrupt the ALC. signal andithus establish'aWorking signaljustasitthe vibrating thread 'had broken. The operator, nobroken thread, is thus .warnedf'of the malfunc'tion of the circuit. Itwill also be noted that thesystern responds as astop page of thespinning operation in thatanyarresf of the thread. 10 necessarily bringsvibrating section 1021 to to rest and the oscillating signal is cutoff.

Although, as indicated above, other electronic or similar circuitarrangements may be employed, and althoughditterent types of components(including the photocell ma be used in the system illustrated, thefollowing ingexampie. v

In the apparatus as constructed, the photoelectric means 24s; a CLZPphotoelectric cell, which has a diameter of cross-section approximately4-inch, i.e. facing the light source. The collimating tube 28 wasaccordingly ametal tube havingan inside" diameter or /4 inch; The lightsource 25 is a small tungsten (incandescent) lamp, sup plied from asuitable 131C. source, or ass volt AC. source. in the circuit of FIG. 5,thecircuit of the photo cell' 24 includ s aresistor 42, of 150,0ooohrns,serving for voltage dividing purposes to apply the correct voltage tothe photocell from the negative terminal of the corres'ponding'powersource. The photocell is coupled through a condenser 44 (0.5 mid.) to agrid of the triode or anode of the tube section 30" is' conaeetedthrough I plate or load resistor 46 220,000 ohms a; the positive side ofthe corresponding power supply. The return of the plate circuit to thecathode extends from ground through a fixed resistor 47 (10,000 ohms)and a further variable resistor 48 (15,000 ohms), by virtue of anadjustable tap 49 on the latter. The ungrountl'ed side of the seriesresistors 47, 48 extends to the negative power terminal. Thus adjustmentof the tap 49 provides a sensitivity controlfor the circuit, i.e. byadjustment of the potential on the plate of tube 30, so as to controlthe grid biaslor sensitivity of tube 32. For by-pass of the alternatingcurrent in the path between the tube cathode and ground, a capacitor 50"isconnected, i.e. be: tween the tapes and ground. This is convenientlyan electrolyticc'onidenser of 5 mfd. M

It will be understood that the voltage across the phototube 24constitutes a DC. component having superimposed thereon a pulsating oralternating component when there is a vierating rticle in the path oflight to the tube. By virtue of the coupling through the capacitor 44,only the AC. component is transmitted to the first amplifier stage,.iue. for application of corresponding alternating potential on the gridof this tube. Ain amplified signal is thus delivered at the plate of thetube, such signal being in effect rectified by the crystaldiodererctifier 3 1- (1N70)" which constitutes the coupling tothe secondamplifier stage This second stage" is provided by the tube 32, being theother half of the dual triode 12Afr7, connectedas' a no.

amplifier. Thus theuinidirectioual voltage is applied from the rectifier31 to the grid of the tube 32 with return from the cathode to ground andwith alternating the latter circuit is in a deenergiz'ed condition whentherelayis ener' zed; and ismo'dified to an energized condition, byclosureofjthe contacts 36, when there is n'ocurrent through the relayl'1 y A power supply of. conventional character maybe provided, e.g-.including a power transfer 54 energizedv from a commercial A.C. line andhaving a high: volt age secondary 55; A pair of silicon rectifiers (M606),

56, 57 are arrangedto rectify alternate half cycles of the current fromthe isecondary 55- and connected to deliver currentin series (as avoltage doubler) so that the positive and negative power supplyterminals are represented as at B] and B= with a point of intermediatepotential (being one side of the secondary 55) connected to ground. Thepower supply includes a suitable protective resistor 58 (47 ohms) andconventional resistor-capacitor filter networks including resistors 59(270 ohms) and as (22,990 ohms). The transformer also has a separatewinding 61 for supplying the heaters 62 of the tube sections 33, 32.

As will now be seen, the effect of a modulated light signal on thephotoelectric cell establishes a corresponding alternating electricalsignal in the control circuit, such A.C. signal being amplified by thetube section 3%, rectified by the crystal diode 3i and converted into anamplified unidirectional current for energization of the relay 34- orsimilar translating device. Under the control of the relay, anappropriate warning signal, as by the light 39 or bell 4% or otherdevice, is furnished when there is no AC. signal, thus representingabsence of a vibrating thread (or absence of vibration in the thread) at16a in FiG. 1. On the other hand, so long as the spinning apparatus isfunctioning properly and the thread Illa is in vibration, thecorresponding signal from the photocell keeps the relay 34 energized andno warning signal is actuated.

Although it will now be appreciated that any of a variety of operationsor devices may be controlled in accordance with the presence or absenceof the vibrating thread or the like, egg. to the extent that drivingmotors may be turned off or other control operation performed as in useof the system with a knitting machine, the illustrated structure affordsappropriate example of the basic instrumentalities and of their use.

As indicated, various modifications may be made, and the procedure andsystem are adaptable for detecting the condition of a passing thread orthe like (Le. any cord-like element) which is under vibration, in a widevariety of equipment and circumstances. Indeed the describedinstrumentalities are applicable to detection or absence of otherarticles, ie where the article is in vibrating or oscillatory condition,such as to indicate its presence by corresponding modulation ormodification of light (as transmitted or reflected to the inspectingphotocell). While other modes of illumination may be employed, includingarrangements where light from a special or natural source is reflectedby the vibrating article, the arrangement shown is of special advantagefor sensitivity and reliability. As explained, the photocell iscontinuously illuminated from the light source, while the effect of thevibrating element is to reduce the illumination in a pulsating oroscillating manner. It will be appreciated that unless otherwise stated,references herein to light and to optical inspection are applicable toradiant energy outside as well as within the visible spectrum, is. sofar as appropriate for detection in modulated form by a sensing devicesuch as a photocell.

It is to be understood that the invention is not limited to the specificembodiments herein shown and described but may be carried out in otherways without departure from its spirit.

I claim:

1. In apparatus which comprises thread-handling mechanism, thecombination, with means for continuously advancing the thread from onelocality through an intervening region to another locality, andcyclically 'moving means engaging said thread at one of said localitiesand imparting thereto a motion producing continuous vibration of thetraveling thread in the aforesaid region, of signal-producing meansincluding photoelectric means disposed to inspect an area occupied bythe vibrating thread in said region, for delivering an alternatingelectrical signal in correspondence with the vibration of the thread,

and means controlled by said signal-prcducing means and selectivelyresponsive to the presence and absence of said alternating signal, toprovide a working signal upon cessation of vibration of the thread.

2. In yarnspinning apparatus which comprises mechanism for continuouslyadvancing yarn being spun from a first locality to a second locality,the combination, with I means delivering yarn from a wound body thereofat said first locality, means for winding the yarn on a receiving bobbinat said second locality, means guiding the yarn through a regionintermediate said first and second localities, and cyclically movingyarn-engaging means rotatable about the receiving bobbin for twistingthe yarn as it is wound thereon by imparting to the yarn a motionproducing continuous vibration of the yarn in the aforesaid region, ofphotoelectric means disposed to inspect an area occupied by thevibrating yarn in said region and adapted to produce an electricaleffect and to indicate the presence of vibrating yarn in said region bymodification of said electrical effect at a frequency corresponding tothe frequency of yarn vibration, circuit means associated with saidphotoelectric means and responsive to its electrical effect, forproducing an alternating current signal in accordance with saidmodification of said electrical effect at said first-mentionedfrequency, and means controlled by said circuit means and including anoutput circuit, for selectively controlling said output circuit inaccordance with the respective presence and absence of said alternatingcurrent signal, to provide a working signal of the absence of vibrationof the yarn as representing interruption of passage of the yarn throughsaid region.

3. Apparatus as defined in claim 2, in which the photoelectric means isdisposed at one side of the region of the vibrating yarn, and whichincludes a light source disposed on the other side of said region sothat light from said source is received by the photoelectric means andis reduced in an oscillating manner by the vibration of the yarn betweenthe source and the photoelectric means.

4. Apparatus as defined in claim 3, wherein the photoelectric meansincludes a collimating tube therefor, aligned with the area occupied bythe vibrating yarn and with the light source, for restricting access oflight to the photoelectric means otherwise than from said source.

5. Apparatus as defined in claim 2, wherein the means controlled by saidcircuit means comprises a relay, arranged to be energized in response tosaid alternating current signal, and having a pair of contacts which areclosed only when the relay is deenergized, and an output circuitconnected with said contacts, for establishing said working signal whenthe contacts are closed.

6. In apparatus which comprises thread-handling mechanism, thecombination, with means for continuously advancing the thread from afirst locality through an intermediate region to a second locality, andcyclically moving means engaging said thread at one of said localitiesand imparting thereto a motion producing continuous vibration of thetraveling thread in said region, of a light source disposed at one sideof said region to direct light through an area occupied by the vibratingthread in said region, photoelectric means disposed at the other side ofsaid region to receive said light and adapted to produce an electricaleffect and to respond to periodic modification of said light resultingfrom the vibration of said thread in said area by modification of saidelectrical effect at a frequency corresponding to the frequency ofthread vibration, circuit means associated with said photoelectric meansand responsive to its electrical effect, for producing an alternatingcurrent signal in accordance with said modification of said electricaleffect at said first-mentioned frequency, and means controlled by saidcircuit means and selectively responsive to the presence and absence ofsaid alternating signal for producing'a positive working signalresponsive to the absence of said alternatingcu-rrent signal,representing cessation of vibration of said thread.

7. In apparatus which comprise thread-handling mechanism, thecombination, with means for continuously advancin the thread from onelocality through an intervening region to another locality, andcyclically moving means engaging said thread at one of said localitiesand imparting thereto a motion producing continuous vibration of thetraveling thread in the aforesaid region, of:

means for illuminating an area occupied by theviorating thread in saidregion in such manner that vibration of the thread creates a pulsatinglight signal; signal-producing means, including photoelectric meansdisposed to inspect said area to detect said pulsating light signal, forproducing an alternating electrical signal responsive only to saidpulsating light signal and in correspondence with the vibration oi thethread, said signal-producing meansbeing constructed and arranged tocease producing said alternating electrical signal in response only tocessation of said pulsating light signal; and means controlled by saidsignal producing meansand selectively responsive only to the presenceand absence of said alternating. electrical signal, to provide a workingsignal upon cessation of said pulsating light signal.

8. In apparatus which comprises thread-handling mechanism, thecombination, with means for continuously advancing the thread from afirst locality through an intermediate region to a second locality, andcyclically moving means engaging said thread at one of said localities.

and imparting thereto a motion producing continuous vibration of thetraveling thread in said reg-ion, of a light source disposed at one sideof said region to direct light through an area occupied by the vibratingthread in said region, photoelectric means disposed at the other side ofsaid region to receive said light and adapted to produce an electricaleffect and to respond to periodic modification of said light resultingfrom the vibration of said thread in said area by modification of saidelectrical effect at a frequency corresponding to the frequency ofthread vibration, said light source and said photoelectric means beingdisposed to permit completely free vibration of said thread in alldirections transverse of its path through said region, circuit meansassociated with said photoelectric means and responsive to itselectrical effect, for producing an alternating current signal inaccordance with said modification of said electrical efiect at saidfirst-mentioned frequency, said photoelectric means and said circuitmeans being constructed and arranged to produce said alternating currentsignal only in response to said periodic modification of said light, andmeans controlled by said circuit means and selectively responsive onlyto the presence and absence of said alternating current signal forproducing a positive Working signal in response only to the absence ofsaid alternating current signal upon cessation of said periodicmodification of said light, representing cessation of vibration of saidthread.

References Qited in the file of this patent UNITED STATES PATENTS2,200,863 Schuck May 14, 1940 2,269,340 Gulliksen Jan. 6, 1942 2,351,229Potts June 13, 1944 2,591,977 Strutt et al Apr. 8, 1952 2,631,273 BagnoMar. 10, 1953 2,728,220 Willner Dec. 27, 1955 2,744,408 Seney May 8,1956 2,892,950 Sadowsky June 30, 1959 3,043,991 Schneider et 9J1 July10, 1962 FOREIGN PATENTS 1,028,155 Germany Apr. 17, 1958 216,854Australia Sept. 2, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No r 5,158,852 November 24, 1964 Gordon E9 Schacher Itis hereby certified that error appears in the above numbered patentreqiiring correction and that the said Letters Patent should read ascorrectedbelow.

Column 2, line 53, for "Suitably" read Suitable column 6, line 68, for"transfer" read transformer a Signed and sealed this 5th day of October1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Allcsting Officer Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,158,852 November 24, 1964 Gordon B, Schacher It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as correctedbelow.

Column 2, line 53, for "Suitably" read Suitable column 6, line 68, for"transfer" read transformer u Signed and sealed this 5th day of October1965.

( SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Al testingOfficer

1. IN APPARATUS WHICH COMPRISES THREAD-HANDLING MECHANISM, THECOMBINATION, WITH MEANS FOR CONTINUOUSLY ADVANCING THE THREAD FROM ONELOCALITY THROUGH AN INTERVENING REGION TO ANOTHER LOCALITY, ANDCYCLICALLY MOVING MEANS ENGAGING SAID THREAD AT ONE OF SAID LOCALITIESAND IMPARTING THERETO A MOTION PRODUCING CONTINUOUS VIBRATION OF THETRAVELING THREAD IN THE AFORESAID REGION, OF SIGNAL-PRODUCING MEANSINCLUDING PHOTOELECTRIC MEANS DISPOSED TO INSPECT AN AREA OCCUPIED BYTHE VIBRATING THREAD IN SAID REGION, FOR DELIVERING AN ALTERNATINGELECTRICAL SIGNAL IN CORRESPONDENCE WITH THE VIBRATION OF THE THREAD,AND MEANS CONTROLLED BY SAID SIGNAL-PRODUCING MEANS AND SELECTIVELYRESPONSIVE TO THE PRESENCE AND ABSENCE OF SAID ALTERNATING SIGNAL, TOPROVIDE A WORKING SIGNAL UPON CESSATION OF VIBRATION OF THE THREAD.